/* this*=this */
public void sqr()
{
norm();
FP2 t1 = new FP2(a);
FP2 t2 = new FP2(b);
FP2 t3 = new FP2(a);
t3.mul(b);
t1.add(b);
t2.mul_ip();
t2.add(a);
a.copy(t1);
a.mul(t2);
t2.copy(t3);
t2.mul_ip();
t2.add(t3);
t2.neg();
a.add(t2);
b.copy(t3);
b.add(t3);
norm();
}
/* this*=y */
public void mul(FP4 y)
{
norm();
FP2 t1 = new FP2(a);
FP2 t2 = new FP2(b);
FP2 t3 = new FP2(0);
FP2 t4 = new FP2(b);
t1.mul(y.a);
t2.mul(y.b);
t3.copy(y.b);
t3.add(y.a);
t4.add(a);
t4.mul(t3);
t4.sub(t1);
// t4.norm();
b.copy(t4);
b.sub(t2);
t2.mul_ip();
a.copy(t2);
a.add(t1);
norm();
}
/* this=1/this */
public void inverse()
{
norm();
FP2 t1 = new FP2(a);
FP2 t2 = new FP2(b);
t1.sqr();
t2.sqr();
t2.mul_ip();
t1.sub(t2);
t1.inverse();
a.mul(t1);
t1.neg();
b.mul(t1);
}